This invention relates to electrooptical scanning devices and more particularly to monolithic laser scanning devices comprising a means for coupling a wide collimated beam of radiation with an integral optical deflection region.
One of the desired aims in electrooptic scanning devices is the provision of a monolithic solid state laser beam scanner wherein a coherent light beam or radiation produced from an internal light or radiation source is coupled directly into a light scanning region operative to cause the far field beam to scan across an image plane or to focus the beam to a spot in the far field and scan the spot across the image plane. The difficulty with such a structure is the complexity of fabrication and the means by which the phase front of the light might be effectively controlled to produce a continuous scanned beam or spot.
An example of a laser beam scanner is disclosed in Ser. No. 918,740 filed June 26, 1978, which is assigned to the assignee herein. The scanner disclosed is of the moving interference fringe pattern type wheren the monolithic structure has a source of coherent radiation and integral wave guiding region for guiding the radiation along a plurality of spatially displaced optically uncoupled paths to produce two or more emitting filaments. By producing a relative phase change from the light in one path relative to another, the interference fringes in the far field can be caused to spatially scan across an image plane.
By introducing an electrically controlled optical phase shift between two or more coherent emitting filaments produced by this monolithic structure, beam direction in the far field can be controlled. The resolution of the beam is directly proportional to the number of emitting filaments. For higher resolution, it is imperative to establish a means of controlling the phase of the radiation light to a predetermined number of coherent optical emitting filaments. For the simplest configuration, this requires at least N+1 electrical contacts to be employed with the structure if N resolvable spots are to be obtained in order that the optical phase of the filaments are properly controlled.
To provide high resolution, such as a monolithic laser beam scanner with 1,000 or more resolvable spots, a large number of contacts greater than 1,000 are required.